The present invention relates to outboard boat motors of the type adapted to be mounted on the transom of a boat and, more particularly, to an improved retainer for preventing the motor from inadvertently moving or coming off the transom in the event the clamping screws are not properly tightened.
A typical outboard motor for a boat includes a transom bracket by which it is attached to the boat and about which the engine and drive unit may be pivoted on a horizontal axis extending laterally through the transom bracket. The transom bracket typically includes a pair of generaly U-shaped clamping members placed over the upper edge of the boat transom. A manually operable thumb screw extends through the leg of each of the U-shaped members inside the boat and includes a clamping pad for demountably clamping the transom bracket to the boat transom. Alternately, the legs of each of the generally U-shaped members may be interconnected with bolts extending through the transom, but this obviously results in an installation in which the motor is not easily removed from the boat.
With most smaller sized outboard motors which are primarily intended to be hand operated by a tiller handle attached to the motor, most operators prefer to be able to readily demount and remove the motor from the boat transom. Therefore, the use of the thumb screw type of clamping assembly is more attractive. However, care must be taken to assure that the thumb screws are adequately tightened and that they do not work loose as a result of vibration or the like during the operation. Operation of an outboard motor with loosened thumb screw clamps may result in the motor sliding laterally along the transom or, in the worst case, the engine under certain conditions of drive unit thrust and steering angle may tilt upwardly on the transom and come completely off the boat. The obvious result is the loss of an outboard motor or, if the motor is chained or otherwise supplementally secured to the boat, the engine may still be submerged or the engine and/or the boat otherwise damaged.
In one prior art device, a plate is attached to the inside face of the transom and includes a horizontal laterally extending rib set at a height which will be just above the clamping pads on the thumb screws when the motor is clamped to the transom. The rib is intended to function to keep the transom bracket and the motor from tilting upwardly and off its mounting on the transom should the thumb screws be left or become untightened. Obviously, however, such a horizontal rib will not prevent a loosened outboard motor from sliding laterally along the transom and possibly beyond the extent of the protecting rib. Furthermore, sufficiently loosened thumb screws may result in a large enough gap such that the clamping pads will completely clear the rib and result in upward movement and possible loss of the motor.
U.S. Pat. No. 3,056,977 shows an outboard motor mounting apparatus which includes a pair of short spaced retaining lips disposed along a horizontal upper edge of the transom, which lips extend outwardly from the transom at an acute angle and terminate in an edge that overlies the edges of the clamping pads normally disposed immediately thereunder. The retainer also includes lateral vertically extending flange portions which provide an abutment to prevent the mounting bracket and motor from moving laterally from the mounting position. However, the limited length of the retaining lips in a lateral direction as well as the short width of the angled free edges thereof are ineffective in preventing loss of the motor under circumstances where the clamping pads are left completely or almost completely open and under certain conditions of engine operation, as indicated above. In particular, if an outboard motor having a conventional clamping bracket is placed on the boat transom, but the thumb screws and attached clamping pads are left in their fully open unclamped position, operation of the motor with reverse thrust and a fairly sharp steering angle results in propellor thrust which will cause the clamping pads to move forwardly out of engagement with the transom and the motor to rotate upwardly and pivot about the opposite lateral edge of the upper end of the clamp bracket resting on the transom. The fully opened clamp pads will not be restricted by and will not engage the prior art retaining lips and, as a result, the motor will likely come completely off of the transom.
Copending U.S. patent application Ser. No. 07/241,629, filed Sept. 8, 1988, entitled "Outboard Motor Retainer", and commonly owned with the subject application, describes a retainer which includes an angled retaining lip that completely surrounds the region of the transom within which the clamping pads might move if loosened. Thus, the retaining lip of that application is intended to prevent either lateral or vertical movement of the motor on the transom if the clamping pads are not tightly clamped or even left completely open. However, in the worst case situation, described above, with the clamping pads left completely open and the motor operated in reverse and in a tight turn, the open clamping pads, which are forced to move forward of and away from the transom as a result of the reverse thrust, might simply ride over the retaining lip, again resulting in loss of the motor.
It would be desirable, therefore, to have a means for more positively retaining the position of a transom-mounted outboard motor should the clamping thumb screws become loosened or be left untightened. Such a retaining means should be capable of preventing lateral movement of the motor along the transom and vertical movement of the motor upwardly and off of its mounting. Most desirably, such a retaining means should be effective to prevent loss of the motor in the worst case situation where the thumb screws and clamping pads are left in their fully opened position. It would also be desirable to have a retaining means which is of simple and inexpensive construction, easily attachable, and would not unreasonably interfere with mounting the motor to or detaching it from the boat transom using a conventional thumb screw type of clamping assembly.